Apple has responded to an open letter from two major shareholders requesting that the company focus more on phone addiction among children, Business Insider reports.

Among other things, the shareholders—Jana Partners LLC and the California State Teachers’ Retirement System—urged Apple to “offer parents more choices and tools to help them ensure that young consumers are using your products in an optimal manner.”

Their request has evidence behind it. San Diego State University Professor Jean Twenge notes, “According to the research, the problem isn’t teens owning smartphones. In fact, teens who don’t use smartphones at all are actually a little less happy than those who use them a limited amount. It’s only when use goes beyond two hours a day that issues begin to appear, including less sleep and a higher risk of suicide-related outcomes such as depression and making suicide plans.”

In a statement to Business Insider, an Apple representative said, “Apple has always looked out for kids […] We lead the industry by offering intuitive parental controls built right into the operating system,” adding, “Of course, we are constantly looking for ways to make our experiences better. We have new features and enhancements planned for the future, to add functionality and make these tools even more robust.”

Tony Fadell, founder of smart thermostat company Nest and one of the designers of the iPhone and iPod, has been an outspoken advocate on this issue. At a 2017 mindfulness summit, Fadell voiced concern that his grandchildren will remember him as “the guy that destroyed society” and mentioned that tech companies should help customers set better boundaries with their products. He has also spoken about the problem of “smartphone dependency,” saying, “I wake up in cold sweats every so often thinking, what did we bring to the world?”

In response to the shareholders’ letter, Fadell tweeted, “they’ve gotten so good at getting us to go for another click, another dopamine hit. They now have a responsibility & need to start helping us track & manage our digital addictions across all usages.”

Apple has not released any details pertaining to these “features and enhancements.”

Read Apple’s full response, and more from Business Insider, here